Effect of Breath Holding on Blood Flow Measurement using Fast Velocity Encoded Cine MR Imaging

Introduction Velocity encoded tine (VEC) MR imaging provides quantitative assessment of blood flow in the cardiovascular system. With use of segmented k-space fast VEC MR imaging, noninvasive assessment of blood flow and vasodilator flow reserve in the coronary artery and coronary arterial bypass graft can be obtained within a single breath-hold time. However, it has been pointed out that blood flow measurement with breath-hold MR imaging may be altered in comparison to the physiological blood flow during regular breathing, since breath holding can change intrathoracic pressure which affects venous return to the heart. Paulev P et al [l] reported that cardiac output was 20-40 percent lower than the control values if subjects held their breath with relatively high intrapulmonic pressure using Valsalva maneuver. The purpose of the current study was to determine if breath-hold MR measurement of blood flow in the aorta and pulmonary artery can be significantly altered in comparison to that measured during regular breathing.